The present invention relates to systems and methods for addressing ambient light in a captured image. The present invention is well-suited for use in touch/multitouch input systems that utilize light reflection to detect screen touches in the presence of ambient light and in machine vision systems that capture images more difficult to process due to the presence of ambient light.
Many machine vision systems are adversely affected by ambient light. The term ambient light refers to the light that is available in a room or other environment, external to a system. Too much ambient light can cause poor perform in machine vision systems by either masking objects or fooling the system with false positives. Ambient light can come from a variety of sources including room lighting, direct and indirect sunlight. These problems can be particularly acute in the context of machine vision systems that have a source of illumination and rely on reflections from the source of illumination as part of the vision system. In many applications of this type, the intensity of ambient light can be significantly greater than the intensity of the light reflecting from the source of illumination. As a result, ambient light can overwhelm the image sensor and mask reflections from the source of illumination, thereby making it difficult for the vision system to operate properly. The problems can be compounded when the amount of ambient light in an environment changes over time. For these reasons it is important to properly account for and guard against ambient light interference in machine vision systems.
A variety of systems and methods have been developed to address the problem of ambient light in the context of multitouch input systems and machine visions systems. Although many of these systems may provide improved performance, there remains a need for a system and method that addresses these problems with a more appropriate balance between cost, efficiency and effectiveness.